Abstract: A microprocessor includes a branch target buffer (BTB). Each BTB entry holds a tag based on at least a portion of a virtual address of a block of instructions previously fetched from a physically-indexed physically-tagged set associative instruction cache using a physical address that is a translation of the virtual address, a translated address bit portion of a set index of an instruction cache entry from which the instruction block was previously fetched, and a way number of the instruction cache entry from which the instruction block was previously fetched. In response to a BTB hit based on a fetch virtual address, the BTB provides a translated address bit portion of a predicted set index that is the translated address bit portion of the set index from the hit on BTB entry and a predicted way number that is the way number from the hit on BTB entry.

Abstract: An instruction fetch pipeline includes first, second, and third sub-pipelines that respectively include: a TLB that receives a fetch virtual address, a tag random access memory (RAM) of a physically-indexed physically-tagged set associative instruction cache that receives a predicted set index, and a data RAM that receives the predicted set index and a predicted way number that specifies a way of the entry from which a block of instructions was previously fetched. The predicted set index specifies the instruction cache set that includes the entry. The three sub-pipelines respectively initiate in parallel: a TLB access using the fetch virtual address to obtain a translation thereof into a fetch physical address that includes a tag, a tag RAM access using the predicted set index to read a set of tags, and a data RAM access using the predicted set index and the predicted way number to fetch the block of instructions.

Abstract: An instruction fetch pipeline includes first, second, and third sub-pipelines that respectively include: a TLB that receives a fetch virtual address, a tag random access memory (RAM) of a physically-indexed physically-tagged set associative instruction cache that receives a predicted set index, and a data RAM that receives the predicted set index and a predicted way number that specifies a way of the entry from which a block of instructions was previously fetched. The predicted set index specifies the instruction cache set that includes the entry. The three sub-pipelines respectively initiate in parallel: a TLB access using the fetch virtual address to obtain a translation thereof into a fetch physical address that includes a tag, a tag RAM access using the predicted set index to read a set of tags, and a data RAM access using the predicted set index and the predicted way number to fetch the block of instructions.

Abstract: A dynamically-foldable instruction fetch pipeline receives a first fetch request that includes a fetch virtual address and includes first, second and third sub-pipelines that respectively include a translation lookaside buffer (TLB) that translates the fetch virtual address into a fetch physical address, a tag random access memory (RAM) of a physically-indexed physically-tagged set associative instruction cache that receives a set index that selects a set of tag RAM tags for comparison with a tag portion of the fetch physical address to determine a correct way of the instruction cache, and a data RAM of the instruction cache that receives the set index and a way number that together specify a data RAM entry from which to fetch an instruction block. When a control signal indicates a folded mode, the sub-pipelines operate in a parallel manner. When the control signal indicates a unfolded mode, the sub-pipelines operate in a sequential manner.

Abstract: A microprocessor includes a branch target buffer (BTB). Each BTB entry holds a tag based on at least a portion of a virtual address of a block of instructions previously fetched from a physically-indexed physically-tagged set associative instruction cache using a physical address that is a translation of the virtual address, a translated address bit portion of a set index of an instruction cache entry from which the instruction block was previously fetched, and a way number of the instruction cache entry from which the instruction block was previously fetched. In response to a BTB hit based on a fetch virtual address, the BTB provides a translated address bit portion of a predicted set index that is the translated address bit portion of the set index from the hit on BTB entry and a predicted way number that is the way number from the hit on BTB entry.

Abstract: An instruction fetch pipeline includes first, second, and third sub-pipelines that respectively include: a TLB that receives a fetch virtual address, a tag random access memory (RAM) of a physically-indexed physically-tagged set associative instruction cache that receives a predicted set index, and a data RAM that receives the predicted set index and a predicted way number that specifies a way of the entry from which a block of instructions was previously fetched. The predicted set index specifies the instruction cache set that includes the entry. The three sub-pipelines respectively initiate in parallel: a TLB access using the fetch virtual address to obtain a translation thereof into a fetch physical address that includes a tag, a tag RAM access using the predicted set index to read a set of tags, and a data RAM access using the predicted set index and the predicted way number to fetch the block of instructions.